DIFFRACTIVE OPTICAL ELEMENTS WITH VARYING DIRECTION FOR DEPTH MODULATION
First Claim
1. An optical system, comprising:
- a substrate of optical material;
a first diffractive optical element (DOE) disposed on the substrate, the first DOE having an input surface and configured as an in-coupling grating to receive one or more optical beams as an input; and
a second DOE disposed on the substrate and configured for pupil expansion of the one or more optical beams along a first direction,wherein at least a portion of the second DOE includes two or more regions in which a depth modulation direction is constant within a region and changes at each transition between regions, the depth modulation direction described by a steepest change of grating depth in the second DOE.
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Abstract
In an optical display system that includes a waveguide with multiple diffractive optical elements (DOEs), one or more of the DOEs is configured with gratings that have varying depth and varying directions for depth modulation, in which the modulation direction is aligned with the steepest change (i.e., slope) of grating depth. Depth modulation direction may change at a point of transition between different regions in the DOE. For example, with a zero axis being defined along a line parallel to a long side of a DOE, the depth modulation direction can change from a negative angle, with respect to the axis in the plane of the waveguide in one region, to a positive angle in another region, or vice versa. By varying depth modulation direction in a DOE, display uniformity in the optical display system may be increased.
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Citations
20 Claims
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1. An optical system, comprising:
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a substrate of optical material; a first diffractive optical element (DOE) disposed on the substrate, the first DOE having an input surface and configured as an in-coupling grating to receive one or more optical beams as an input; and a second DOE disposed on the substrate and configured for pupil expansion of the one or more optical beams along a first direction, wherein at least a portion of the second DOE includes two or more regions in which a depth modulation direction is constant within a region and changes at each transition between regions, the depth modulation direction described by a steepest change of grating depth in the second DOE. - View Dependent Claims (2, 3, 4, 5)
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6. An electronic device, comprising:
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a data processing unit; an optical engine operatively connected to the data processing unit for receiving image data from the data processing unit; an imager operatively connected to the optical engine to form images based on the image data and to generate one or more input optical beams incorporating the images; and an exit pupil expander, responsive to the one or more input optical beams, comprising a structure on which multiple diffractive optical elements (DOEs) are disposed, one or more of the DOEs being configured with gratings of varying depth, in which the exit pupil expander is configured to provide one or more output optical beams, using one or more of the DOEs, as a near eye virtual display with an expanded exit pupil, and wherein one or more of the DOEs is configured to include two or more regions in which depth modulation direction is different in each of the two or more regions, the depth modulation direction in a region being a direction for which a rate of change of grating depth is greatest. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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15. A method, comprising:
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receiving light at an in-coupling diffractive optical element (DOE) disposed in an exit pupil expander; expanding an exit pupil of the received light along a first coordinate axis in an intermediate DOE disposed in the exit pupil expander; expanding the exit pupil along a second coordinate axis in an out-coupling DOE disposed in the exit pupil expander; and outputting light with an expanded exit pupil relative to the received light at the in-coupling DOE along the first and second coordinate axes using the out-coupling DOE, in which the intermediate DOE is configured with at least two regions wherein a depth modulation direction in a first region of the at least two regions has a negative angle in a plane of the intermediate DOE with respect to a zero axis and a depth modulation direction in a second region of the at least two regions has a positive angle in the plane with respect to the zero axis, wherein depth modulation direction is described by a steepest change of grating depth in each respective region. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification